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Spectroscopy and redox chemistry of copper in mordenite

Vanelderen, Pieter and Vancauwenbergh, Julie and Tsai, Ming-Li and Hadt, Ryan G. and Solomon, Edward I. and Schoonheydt, Robert A. and Sels, Bert F. (2014) Spectroscopy and redox chemistry of copper in mordenite. ChemPhysChem, 15 (1). pp. 91-99. ISSN 1439-4235. https://resolver.caltech.edu/CaltechAUTHORS:20180612-145906146

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Abstract

Copper-containing zeolites, such as mordenite (MOR), have recently gained increased attention as a consequence of their catalytic potential. While the preferred copper loadings in these catalytic studies are generally high, the literature lacks appropriate spectroscopic and structural information on such Cu-rich zeolite samples. Higher copper loadings increase the complexity of the copper identity and their location in the zeolite host, but they also provide the opportunity to create novel Cu sites, which are perhaps energetically less favorable, but possibly more reactive and more suitable for catalysis. In order to address the different role of each Cu site in catalysis, we here report a combined electron paramagnetic resonance (EPR), UV/Vis-NIR and temperature-programmed reduction (TPR) study on highly copper-loaded MOR. Highly resolved diffuse reflectance (DR) spectra of the CuMOR samples were obtained due to the increased copper loading, allowing the differentiation of two isolated mononuclear Cu^(2+) sites and the unambiguous correlation with extensively reported features in the EPR spectrum. Ligand field theory is applied together with earlier suggested theoretical calculations to determine their coordination chemistry and location within the zeolite matrix, and the theoretical analysis further allowed us to define factors governing their redox behavior. In addition to monomeric species, an EPR-silent, possibly dimeric, copper site is present in accordance with its charge transfer absorption feature at 22200 cm^(-1), and quantified with TPR. Its full description and true location in MOR is currently being investigated.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1002/cphc.201300730DOIArticle
ORCID:
AuthorORCID
Hadt, Ryan G.0000-0001-6026-1358
Solomon, Edward I.0000-0003-0291-3199
Additional Information:© 2014 WILEY‐VCH. Received: August 7, 2013. This work was performed within the framework of FWO (G.0596.11), IAP (Belspo), ERIC (European Union), Methusalem (long‐term structural funding by the Flemish Government) projects, and supported by National Science Foundation Grants CHE‐0948211 (to E.I.S.). M.‐L.T. received supports from the Postdoctoral Research Abroad Program sponsored by the National Science Council, Taiwan (R.O.C.) and R.G.H. acknowledges a Gerhard Casper Stanford Graduate Fellowship and the Achievement Rewards for College Scientists (ARCS) Foundation.
Funders:
Funding AgencyGrant Number
Fonds Wetenschappelijk Onderzoek (FWO)G.0596.11
Belgian Federal Science Policy Office (BELSPO)UNSPECIFIED
NSFCHE‐0948211
National Science Council (Taipei)UNSPECIFIED
Stanford UniversityUNSPECIFIED
ARCS FoundationUNSPECIFIED
Issue or Number:1
Record Number:CaltechAUTHORS:20180612-145906146
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20180612-145906146
Official Citation:Vanelderen, P. , Vancauwenbergh, J. , Tsai, M. , Hadt, R. G., Solomon, E. I., Schoonheydt, R. A. and Sels, B. F. (2014), Spectroscopy and Redox Chemistry of Copper in Mordenite. ChemPhysChem, 15: 91-99. doi:10.1002/cphc.201300730
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:87029
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:12 Jun 2018 22:12
Last Modified:03 Oct 2019 19:51

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